1. Field of the Invention
The present invention relates to an electric rotating machine mounted on a vehicle such as a passenger car or a truck.
2. Description of Related Art
There is known a vehicle generator provided with a power conversion apparatus including a power converting section having switching elements to rectify the output voltage of an armature winding of the vehicle generator. For example, refer to Japanese Patent No. 4275704. The power conversion apparatus described in this patent controls each of the switching elements such that a diode conduction state ends after lapse of a predetermined off-ensuring time from when the switching element is turned off, so that a current can be prevented from flowing to the armature winding from a vehicle battery.
The above power conversion apparatus is configured to store a timing at which a diode conduction state ends, and to turn on the switching element at a timing earlier than this stored timing by the off-ensuring time. However, this power conversion apparatus has a problem in that since a timing at which a diode conduction state ends varies significantly when a vehicle driver operates the accelerator pedal to accelerate the vehicle, or when electrical load increases sharply, there may occur a case where the switching element cannot be turned off at proper timings ensuring the off-ensuring time. It might occur that the off-ensuring time is set longer. However, in this case, since power loss increases, the power generation efficiency is lowered.